Technical Field
The disclosure is related to process gas distribution in a plasma reactor for processing a workpiece such as a semiconductor wafer.
Background Discussion
Control of process gas distribution in the chamber of a plasma reactor affects process control of etch rate distribution or deposition rate distribution on a workpiece during plasma processing. Gas injection nozzles can be located at the center and periphery of the chamber. It is desirable to control gas injection at both the chamber center and at the periphery. One problem is that systems that control radial distribution of process gas flow rate generally do not control azimuthal distribution of process gas flow rate. As employed in this specification, the term “azimuthal” refers to the circumferential direction in a cylindrical processing chamber. Another problem is that systems that control azimuthal distribution of gas flow rate using gas injectors near the side wall suffer from pressure drops along the azimuthal direction.
A related problem is how to feed process gas to different zones of gas injectors in such a manner as to avoid asymmetries in gas distribution while at the same time providing full control of both radial and azimuthal gas distributions.
Another problem is how to provide a gas distribution system that solves all of the foregoing problems in a structure affording rapid disassembly and re-assembly with close-fitting tolerances without damage.
The formation of gas distribution passages in one layer has generally limited the location of the gas injectors of the chamber to that one layer, which is typically flat and has no particular effect upon gas flow within the chamber.